The diameter of expansion shafts can be changed in a controlled manner so that cores with rolls of material wound onto them with the help of the expansion shafts can pivot and if necessary be driven. In order to enable the expansion shafts to change their diameter they are provided with apertures through which clamping devices penetrate in radial direction to the shaft in order to effect the necessary change of the external diameter of the expansion shaft. An example for expansion shafts of this kind can be found in U.S. Pat. No. 4,773,656 and in the German design registry No. DE-U-86 34 752.
The tubes of conventional expansion shafts are made of steel or aluminum. In order to apply the apertures to the tube, a steel tube is machined accordingly. This procedure is very labor intensive. Furthermore, a tube of this kind is quite heavy due to the metal used.